A known headrest support device for a vehicle seat supports a headrest so as to be angularly adjusted relative to a seatback (see Patent Document 1, for example). The headrest support device disclosed in Patent Document 1 includes a pillar structure including a pair of right and left leg portions having lower ends coupled to a seatback and a horizontal rod portion connected between the upper ends of the leg portions, a main frame rotatably supported by the horizontal rod portion, and a cover material that covers the main frame. The headrest is completed by covering the cover material with a pad material and a skin member.